Telephone system



Aug. 6, 1929.

H. M. BASCOM TELEPHONE SYSTEM Filed June 0, 1928 INVENTOR I BY EfllflmwmATTORN EY Patented Aug. 6, 1929.

UNITED STATES PATENT OFFICE.

HENRY M. BASCOM, OF BROOKLYN, NEV] YORK, ASSIGNOR TO AMERICAN TELEPHONEAND TELEGRAPH CGBIPANY, A CORPORATION OF NEJV' YORK.

TELEPHONE SYSTEM.

Application filed June 20,

This invention relates to telephone systems, and more particularly. totelephone metering systems in which the subscriber is charged for thenumber of calls made or completed, or for the length of each call, orfor both the number of calls made and the length of each call.

In such systems it has been proposed to employ a simplex circuit tooperate the recording meter located either at the substation or at thecentral otlice. This simplex circuit comprises an impedance bridgeacross the line of the subscriber to be charged, metering apparatusincluding a marginal relay connected from the midpoint of said bridge toground, a second impedance bridge adapted to be connected across thecord circuit at the central oiiice and a grounded direct current sourceconnected to the midpoint of the latter bridge for trans mittingimpulses over both sides of the subscribers line in parallel to operatethe me tering apparatus.

This system, as heretofore employed, was found to have certainobjectionable features which interfered with the efiiciency of theregular transmission of speech signals. The connection of the secondbridge, described above, across the cord circuit when impulses werebeing transmitted over the subscribers loop, resulted in theestablishment of a local circuit including the bridge, the cordconductors, the talking current battery and the impedance or repeatingcoils of the battery supply bridge. This local circuit partially shuntedthe talking current and hence great- 1y decreased the talking currentflowing through the substation circuit. Obviously, this seriouslyinterfered with the efficiency of the transmission of speech signals.Likewise, the sudden decrease in the talking current flowing through thesubstation circuit produced objectionable disturbances in the talkingcircuit. Also, the establishment of this local circuit partially shuntedthe meter operating current and thus substan tially reduced theeffective meter operating current flowing through the meter relay.

It is an object of this invention to provide an improved telephonemetering system embodying a simplex circuit for meter operation in whichthe objectionable features pointed out above are eliminated and in whicha hi h de ree of eliicien 7 is attained.

'Ilhe tion con I com- 1928. Serial No. 286,991.

bination with a telephone system of an impedance or inductance bridgeacross the line of the subscriber to be charged, a meter connected fromthe midpoint of said bridge to ground, a talking current supply bridgeacross the cord circuit, including a pair of impedance or repeatingcoils, a talking current source connected to said current supply bridgeand means adapted to be connected to the midpoint of said current supplybridge for impressing impulses on both sides of the subscribers line inparallel to operate said meter.

A better understanding of the invention may be had from the detaileddescription hereinafter following.

In the drawing, Figure 1 represents diagrammatically a telephone circuitillustrating the preferred embodiment of the invention, and Fig. 2represents diagr'annnati call a telephone circuit illustrating anotherform of the invention.-

In Fig. 1 there are shown two subscribers stations A and B, withsubscribers loops extending to the central oflice and terminating in thejacks 13 and 13. As shown, A represents the station of the callingsubscriber and B that of the called subscriber. The substations comprisethe usual transmitters l and 1', the receivers 2 and 2', the receiverhooks 3 and 3, the contacts 4. and 4', and 5 and 5', respectively, theinduction coils 6 and 6, the ringers 7 and 7, and the condensers 8 and8. In addition, there are located at the substations impedance orinductance bridges 9 and 9 adapted to be connected across thesubscribers lines. Registers 10 and 10 are adapted to be connected fromthe midpoints of said bridges through the receiver contacts 12 and 12 toground at 11 and 11.

The cord circuit C of the central office is here illustrated as theimpedance coil feed type. Obviously, a cord circuit of the repeatingcoil teed type may be used, if dcsired. The cord circuitshown comprisesthe usual current source 14 grounded at its midpoint at 15, the talkingcurrent supply bridge 16 of the calling subscribers line, the talkingcurrent supply bridge 17 of the called subscribers line, each of saidsupply bridges including a pair of impedance coils, the capacities 18and 18', supervisory relay 19and he cord conductors 20 20, 21 and ay,talking 11 at snj iply bridge 16 is connected directly to the source 14through the leads 27 and 27, the contacts 28 and 28 and the armatures 29and 29. A means for impressing impulses on the line is adapted to beconnected to the current supply bridge 16 through the leads 31 and 31,the contacts 32 and 32 and the armatures 29 and 29. This means comprisesthe direct current induction generators 22 and 22 and the energizingcircuit 28, the latter comprising the induction coils 24 and 2st, thecurrent source 25 and the switch 26. As shown, the switch 26 is oit'therheostat type in order that the building-up and the decay of thegenerator field may be gradual and smooth to prevent objectionabledisturbances in the talking circuit. It is obvious, how ever, that asimple switch may be used and the generator field itself so designedthat the length of time required for the buildingup and the length oftime required for the decay of the field are approximately equal. Arelay circuit 40 under the control of a clock mechanism ll is providedfor periodi cally closing the switch 26 to energize the generators 22and 22. A switching mechanism 30 under the control of the relay 19 isassociated with the cord circuit for breaking the direct connection ofthe bridge 16 with the source 14 and for reconnecting it to said sourcethrough the generators 22 and 22. This switching mechanism comprises therelay 33 grounded at 34, the armatures 29 and 29, the conductor 35, thearmature 36, the contact 87 and the source 88 grounded at 39. A filterelement 42 is connected across the leads 31 and 81 to prevent any objectionable disturbances in the talking circuit. Leads 43, l l5 and 46 areprovided for associating source 14 and the impulse impressing means withthe other connecting circuits of the central ofiice.

As shown, the current source 141- is ground ed at its midpoint at 15. Inthe systems heretofore employed, the central oilice battery wasgrounded. at one terminal, which fact necessitated the use of metershaving marginal relays in order to prevent false registration due to theground potential difference between the ground connections of the metersand that of the central oflice battery. In the present arrangement, asbe:

tween the groundconnections of the meters and that of the source 1 1-,there is no ground potential difference and hence meters havingnon-marginal relays may be used. However, it should be understood thatmeters having marginal relays may be used if desired.

The operation of the system is as follows: V fhen the calling subscriberat station A removes his receiver from the hook to initiate a call, aconnection is established to the central otlice in the well-knownmanner. At this time a current of normalline voltage is flowin throughthe substation cir-' the connection has been completed through the cordcircuit C to station B of the called subscriber, and when the ca ledsubscriber removes his receiver from the hook, the circuit including thesupervisory relay 19 is closed in the manner well known to thosefamiliar with the art. The closure of this circuit and the resultingenergization of tee supervisory relay 19 causes the latter to attractits armature 36, which establishes a connection with the contact 37. iThe establishment of this connection closes the circuit of the relay 33and causes its energization. When energized, this relay attracts itsarniatures 29 and 29 to break their con nection with the contacts 28and28', re spectively, and to establish their connection with contacts32 and 32, respectively. This breaks the direct connection of the bridge16 with the source 14 and reconnects it to said source through thegenerators 22 and 22 and the leads 31 and 31'. At predeterminedintervals of time the clock mechanism 21 closes the relay circuit 40,which in turn causes the closure of the switch 26 and energizes theinduction cells 2 1 and 24. The generators 22 and 22 are energized antimpress an impulse through the bridge 16 on both sides of the line inparallel through the bridge 9 to operate the meter 10. Thus, the impulsewhich passes over the simplex circuit does not in any way interfere withthe talking current or speech signals. The circuit traversed by thesecurrent impulses includes the ground 15, the source 14-, the generators22 and 22, the leads 31 and 31, the contacts 32 and 32, the armatures 29and 29, the current supply bridge 16, the cord conductors 20 and 21, thejack 13, both si oi the called subscribers line, the bridge 9, thecontacts 12, the relay of the meter 10 and the ground 11. When thereceivers are re turned to the hooks, the meter, as well as the bridge 9and the impulse impressing means, is removed from the circuit.

As can be seen from the above description, an improved simplex meteringsystem is provided in which the talking current supply bridge is usedfor transmitting both the talking current and the meter operatingcurrent over the subscribers loop and in which the talking currentsource is grounded at its midpoint; This new arrangement eliminates thenecessity of using a separate bridge,- with its inherent objectionableresults, for transmitting the meter operating 7 impulses over thesubscribers loop. I

Fig. 2 of the drawing illustrates embodiment oft-the invention inWhich-an addi- Ill) tional talking current source 22 is used and inwhich the impulse impressing means comprises a single direct currentinduction generator 23 connected to the midpoint of the source 22. \Vhenthe called subscriber answers, the switching mechanism 31 dis connectsthe calling line from the source l-i and connects it to the source 22which is grounded at its midpoint at 24 through the generator 23. Atpredetermined intervals of time the generator 23 is energized andimpresses an impulse on both sides of the calling line in parallel tooperate the meter, as shown in Fig. 1 and described above.

In the drawing, a telephone system is illustrated in which the callingsubscriber is charged for the length of time his instrument is used forconversational purposes. However, it is to be understood that thisinvention may be embodied in systems in which the subscriber is chargedfor the number of calls made, or for both the number of calls made, andthe length of each call, or in which the charges are made on themultiple basis. 1

As shown and described, the impulse impressing means is connected on oneside of the cord circuit only, since in general it is desirable tocharge the call to the calling subscriber only. It is obvious, however,that the same'mechanism could be applied on the other side of the cordcircuit, or on both sides of the cord circuit, if desired. The impulseimpressing means may be common to all the cords, or to a group of cords,or, if desired, may be supplied for each cord separately. Likewise, saidimpulse impressing means may, be associated with the cord circuit insuch a manner that the operation of the meter will begin at any desiredtime during the connection.

lVhile this invention has been illustrated in connection with a typicalcord circuit using manual operation, it is apparent that it is equallyapplicable to machine switching apparatus.

lVhat is claimed is:

1. In a telephone system, a plurality of subscribers lines, meansincluding a talking current supply bridge for establishing a talkingcircuit between two of said lines, means for closing a circuit includingsaid talking current supply bridge and two sides of said talking circuitin parallel, bridging means across said circuit, and a measured servicedevice connected to said bridging means and controlled over saidcircuit.

2. in a telephone system, subscribers lines, bridging means across saidlines, measuring apparatus connected from said bridging means to ground,connecting circuits for establishing talking connections between saidlines, a talking current supply bridge across each of said connectingc':euits, and means for impressing impulses through said talk ingcurrent supply bridge on two sides of said lines in parallel to operatesaid measur ing apparatus.

3. In telephone system, subscribers lines, bridging means across saidlines, measuring apparatus connected from said bridging means to ground,connecting circuits for establishing talkin connections between saidlines, a talking current supply bridge across each of said connectingcircuits, each of said talking current supply bridges including aplurality of impedance elements, and means for impressing impulsesthrough said talking current supply bridge on two sides of said lines inparallel to operate said measuring apparatus.

a. In a telephone system, subscribers lines, bridging means across saidlines, nonmarginal registering means connected from said bridging meansto ground, connecting circuits for establishing talking connectionsbetween said lines, a current source grounded at its midpoint andadapted to supply talking current to said lines, and means forimpressing impulses on both sides of said lines in parallel to operatesaid registering means.

5. In a telephone system,. subscribers lines, bridging means across saidlines, nonmarginal registering means connected from said bridging meansto ground, connecting circuits for establishing talking connectionsbetween said lines, a talking current supply bridge across each of saidconnecting ciruits, a current source grounded at its midpoint andadapted to supply talking current to said lines, and means forimpressing impulses through said talking current supply bridge on bothsides of said line in parallel to operate said registering means.

6. In a telephone system, a calling line and a called line, a bridgeacross said calling line, registering means'connected from said bridgeto ground, connecting circuits for establishing talking connectionsbetween said lines, a current source adapted to supply talking currentto said calling line, a talking current supply bridge for said callingline, and means for periodically impressing impulses through saidtalking current supply bridge on both sides O'i said calling line inparallel to operate said registering means.

7. In a telephone system, a calling line and a called line, a bridgeacross said calling line, metering apparatus connected from the midpointof said bridge to ground, connecting circuits for establishing talkingconnections between said lines, said connecting circuits including atalking current supply bridge for said calling line and a talkingcurrent supply bridge for said called line, a current source normallyconnected directly to said supply bridges and adapted to supply talkingcurrent to said lines, means adapted to impress impulses perm-(in callyon both sides of said calling line in parallel to operate said meteringapparatus, and means controlled by the closure of the circuit of saidcalled line for breaking the direct connection of said current source tothe talking current supply bridge of said calling line and forreconnecting said current source to the talking current supply bridge ofsaid calling line through said im pulse impressing means.

8. In a telephone system, a calling line and a called line, a bridgeacross said calling line, non-marginal metering apparatus connected fromthe midpoint of said bridge to ground, connecting circuits forestablishing talking connections between said lines, a talking currentsupply bridge for said calling line, a talking current supply bridgei'or aid called line, a current source grounded at its midpoint andnormally connected directly to both of said current supply bridges,means adapted to impress impulses on both. sides of said calling line inparallel tooperate said metering apparatus, filtering means locatedbetween said impulse impressing means and said calling line, means controlled by the closure of the circuit of said called line 'for breakingthe direct connection'of said current source to the talking currentsupply brldge of said calling line and for reconnecting said currentsource to the talking current supply bridge of said calling line throughsaid impulseimpressing means, and means for operating said impulseimpressing means at predetermined intervals of time.

9. In a telephone system, a calling line and a called line, a bridgeacross said calling line, registering means connected from said bridgeto ground, connecting circuits for establishing talking connectionsbetween said lines, each of said connecting circuits including a talkingcurrent supply bridge for said calling line and a talking current supplybridge ior said called line, a current source common to said connectingcircuits and normally connected directly to said talking current upplybridges, means common to said connecting circuits for impressingimpulses on both sides of said calling line in parallel to operate saidregistering means, and means individual to each connecting circuit forbreaking the direct connection of said current source to the talkingcurrent supply bridge of said calling line, and for reconnecting saidsource to the talking current supply bridge of said calling line throughsaid impulse impressing means.

In testimony whereof, I have signed my name to this specification this19th day of June, 1928.

HENRY M. BAsooM.

